java.lang.NoClassDefFoundError when trying to run in NetBeans 6.9 in Windows XP

As the title says, I'm getting a main java.lang.NoClassDefFoundError when trying to run my program within NetBeans 6.9 in windows xp. The culprit is an external Jar Library in another path on my harddrive. In my library properties of my main project, I am adding the library as a project, so it will compile the external project and place it in my "dist" directory. The "build in classpath" box is checked also. Everything complies fine but still the runtime error. An example of he paths would look like the following: